69 GMC 3/4 2wd, 350-4bbl/4spd. In the begining the the truck would hesitate, after sitting in traffic too long. We figured vaporlock. We have added a spacer, replaced the carb,(edelbrock 600) replaced and rerouted the fuel line, replaced all the filters, pump is new, fuel pressure was excellent, adjusted points/timing/dwell, even took apart the new carb to verify it was clean. The truck never overheats, gauge has never even gone halfway up. Nothing has changed. If you run the truck for a while and shut it down, and let it sit for a few minutes, it is almost impossible to restart, and when you give it gas, you can hear it just sucking air. It sounds like it's not getting gas. Have I missed anything?